Non-shrinking seam and method of making



Feb. 3, 1959 c;|n TAo KwoK 2,871,486

' NoN-SHRINKING sEAM AND METHOD oF MAKING Filed June e, 1955 INVENTOR CHI TAO. KwoK ATTORNEY United States Patent NON-SHRINKING SEAM AND METHOD F MAKING Chi Tao Kwok, Troy, N. Y., assignor to Cluett, Peabody & Co., Inc., Troy, N. Y., a corporation of New York Application June 6, 1955, Serial N o. 513,271

2 Claims. (Cl. 2-275) This invention concerns a method of manufacturing a seam which obviatesor at least alleviates the problem of seam shrinkage. When two or more fabrics which are perfectly stable, that is which show no tendency to shrink, are sewn together, and then laundered, they heretofore would inevitably shrink and shorten alo-ng the seam. Seam shrinkage is the pucker or contraction which occurs upon laundering at seams, especially at those seams in which several plies of fabric are joined. It is a wellknown and much studied problem in the textile industry. The pucker is unsightly and unattractive and seriously detracts from the appearance of a garment, but more than that, and perhaps more important, it represents a dimensional change which causes fitted garments to become too tight or too short.

It is self-evident that in a seam the several plies are squeezed tightly together by the sewing thread and will, when conditions permit, tend to resume their normal plump equilibrium condition. The swelling eects of water on cellulosic fabrics permit this readjustment, and the swelling plasticizing and lubricating effects of water and heat promote similar release for the more hydrophobic fabrics. The small quantity of fabric yarns encircled by the threads of a single stitch when swelled by water become thicker and the vertical (normal to the seam) diameter of the stitch must become greater, which it can only do at the expense of the horizontal diameter, that is, the length of the stitch. Obviously, as each stitch becomes shorter, the seam becomes shorter.

I have discovered a simple, economical, and commercially feasible method of introducing a small amount of excess thread in approximately each stitch. With this excess thread distributed along the line of stitches, the stitches and the seam can become thicker without becoming shorter and seam shrinkage does not take place. i have discovered a means of producing a relatively loose seam neverbefore possible under the conditions of cornmercial sewing, that is high sewing speeds and high thread tension.

I have discovered a method of producing under the commercially acceptable conditions of high speed sewing and high thread tension, an adequately loose seam which shows little or no tendency to pucker or shrink as made` or when laundered. The method comprises sewing into the seam, in a manner analogous to the way the plies of fabric are themselves engaged in the seam, a narrow strip of a comb-like structure which may be, for instance, the ravelled fringe of a fibrous or metallic web. The ends of the fibers or metallic strands engaged in the seam are then withdrawn easily by pulling the comb-like structure laterally away from the seam. There results a loose seam, and the degree of loosenes is a function only of the easily controlled conditions of the number and size of extraneous bers or strands the thread was forced to encompass temporarily.

The process, although very easily understood and used, is most readily described with the aid of the drawmgs.

Fig. 1 is a face view of a comb-like structure that may be employed, in this instance a narrow strip of woven material ravelled back a short distance from one edge shown approximately three times its size;

Fig. 2 is a plan view of a portion of a seam showing the manner in which the projecting fibers or filaments of the comb-like structure are engaged in the seam;

Fig. 3 shows a section view of the same seam portion before the comb-like structure is removed from the seam;

Fig. 4 shows the same seam section after the comb-like structure has been removed; and

Fig. 5 is a sectional view similar to Fig. 3 showing the comb-like structure made up of smaller diameter filaments.

1n Figs. 2 to 5 the parts are shown at approximately twenty times their normal size.

Fig. 1 shows a typical example of a satisfactory comblike structure. The free ends of the lingers or filaments 1 project for a length which is not critical but conveniently should be from about one-quarter to about three-quarters of an inch. These projecting elements should be essentially monofilaments. A few'coarse filaments might be plied together to make what might be called polylaments which would still be serviceable but a true multifilament of more than about ten filaments or fibers in its cross-section is too crushable to be useful in this invention.. Mono-filaments then are indicated, but the word monofilament should be understood as including as an equivalent, an aggregate of a small number of filaments functioning as one. True monofilaments, such as for instance bristles, plastic monofilaments or metallic wires are preferred. The comb-like structure is disposed along the seam with its fingers or bristles projecting across the line of sewing so that as the seam is formed, the lingers will be sewn to the fabrics. The several plies of fabric 2 are joined in the usual way by the sewing thread except that the free endsl 3 of the projecting lingers or filaments of the comb-like structure Fig. l are also encompassed in the seam by the sewing thread 4.

An important feature of the discovery is that an element of randomness is permissible. The projecting ngers or filaments 1 of the comb-like structure Fig. l are not, and need no-t be, synchronized with the needle or the frequency of the stitches. A stitch loop 5 may encompass one or several of these free ends 3 or an occasional stitch loop 6 may fail to enclose any of the free ends 3 of extraneous filaments. It is not necessary that there be slack, i. e. excess thread,'in every single stitch, nor is it necessary that the degree of slackness be precisely equal in each stitch. it is only necessary that there be adequate excess thread in the length of seam and that the slack be reasonably dispersed along the seam. These conditions are met by the use of filaments of the proper size, shape, and frequency. The preferred size, shape and frequency will be discussed later in this specification. The free ends 3 of the fibers 1 project through the stitch loops 5 a short, non-critical distance, conveniently from about one to about iive-sixteenths of an inch. The comb-like structure is shown for convenience on top of the plies of fabric 2, but obviously it can just as readily be inserted beneath the several plies or among them. The several plies of fabric are joined by the needle thread 4 and the bobbin thread 7. @ne of the threads, 4 or 7, in this instance the sewing thread 4,-encircles or confines in the seam the projecting filaments or fingers 1 of the comblike structure. Fig. 4 is a sectional view of the same portion of the same seam of Fig. 1 and Fig. 2 after the comb-like structure has been removed. The slackness in the needle thread 4 is shown. In such a seam, swelling of the fabric plies 2 will not cause appreciable shrinkage or pucker along the seam.

The chemical nature of the monoiilament or quasi monofilament is naturaliy not important to its function in this process. it is only necessary that it be reasonably rigid. As far as i know, any mon'olament of the proper size would meet this requirement. h'fonc-tilaments of the common fiber forming plastics such as polyhexamethylene adipaniide, polyetbylenegiycol terephthalate, polyvinyl chloride or chloracetate, polyacrylonitrile, polyvinylidene chloride Vand polyvinylidene nitrile are satisfactory. Hog bristles and other anirnai bristle such as are commonly used in paint brushes can be used. Wires from wire forming metals such as brass, copper or steel are also satisfactory.

The optimum shape for the filaments is that they hc round, but laments of the proper size will function no matter what their shape. We prefer that they be round or nearly round because it is a desirable condition and easily realized.

The size and number of the filaments are related in determining the degree of shrinkage control which is obtained. T he more filaments embraced in each stitch loop, the smaller each filament need be. l prefer that the diameter of the filament range fro-m about .004 to .025 inch. The number of filaments per inch in the comblike structure can be about as few as there are stitches per inch of seam, nominally there are about 8 to about in most garment seams. be as much as can be crowded into a jammed structure, for instance about 100 per inch if they are each .010 inch in diameter.

A few examples of the utility and operability of the process of this discovery are otfered. The seams in these examples were made on standard industrial sewing machines manufactured by a large producer of such equipment. The machines were operated at full speeds which were for machine A used in Examples l, 2 and 3, 3500 stitches per minute and for machine E used in the remainder of the examples, 5500 stitches per minute. The thread tensions and other operating conditions were completely standard, exactly as recommended by the manufacturer of the machines. Cotton sewing thread was used in all the examples, a 70--3 cord thread in the needle and an 80-2 cord in the bobbin.

Example 1 lFour plies of cotton broadcloth shifting, 136 x 60, 4.0 yards per pound and showing zero fabric shrinkage were sewn together with a double'row of stitches as the control plaque. The plies were about 6 inches wide and two feet long. The seams were sewn parallel about one-quarter inch apart down the center of the plaque. In this example, the machine was set for 20 stitches per inch. A test plaque of four plies of the same broadcloth The number of filaments can shirting was made under precisely the same conditions Sample: Shrinkage, percent Control plaque 6.9 Plaque prepared with .010 filaments 1.0

Example 2 A control and a test plaque were prepared from broadcloth such as used in Example 1, in a corresponding They were then 4 manner. Conditions were the same except that 18 stitches per inch were used and the comb-like structure used to prepare the test piece was the frayed edge of a nylon monotilament webbing. The filaments were round and .012 inch in diameter and there were 58 per inch of edge. The eighteen inch marks wereplaced on the seams and the two plaques were subjected to one standard cotton wash cycle as were those of Example 1. They were press dried without stretching, and measured for shrinkage.

Sample: Shrinkage, percent Control plaque 3.6 Plaque prepared with .012 iilaments 1.5

Example 3 in this test, everything-the fabric, the comb-like structure and the other conditions of the test were prepared and used exactly as in Example l, except that sixteen stitches per inch were used rather than twenty. The shrinkage results were as follows:

Sample: Shrinkage, percent Control plaque 3.2 Plaque made with .010 filaments 0.

Example 4 ln this and the following examples, a higher speed sew ing machine was used and operated at about 5500 R. P. M. Well shrink-proofed nylon shirting (122 x 68, 100 den. nylon warp, 50/1 cotton count, spun nylon filling) was used as the fabric to form the plaques. Cotton thread was used as in all the examples. The seams were prepared with sixteen stitches per inch. The comb-like structure was made of polyvinylidene chloride monolaments. Those entering the seam were round, .012 inch in diameter and there were 60 per inch.

A control plaque of four plies of the nylon shitting and a similar plaque temporarily incorporating the polyvinylidene chloride monofilaments described above were prepared, marked, laundered, and measured for shrinkage. The laundering procedure used was the American Institute of Laundering, White Family Wash Cycle.

Sample: Shrinkage, percent Control plaque 3.8

Plaque made with .012 filaments 0.8

' Example 5 Exactly as for Example 4, except that a Dacron (polyethyleneglycol terephthalate) shirting was used. The fabric structure was 144 X 74, 70 denier Dacron in each direction.

As in the other examples, a control plaque and a test plaque were prepared. In this instance the comb-like structure of Example 4 was used to ensure the avoidance of excess tightness in the test seam. The Dacron plaques were laundered together using the wash cycle identified in Example 4.

Sample: Shrinkage, percent Control plaque 3.2 Plaque made with .012 filaments 0.3

Example 6 Soft collars of the type attached to mens business shirts were prepared for this test. The collars consisted of two parts, the top and the band and each of these parts consisted of three layers, the outer faces and the lining. For these collars the broadcloth shirting identified in EX- ample 1 was used for the outer faces or plies of both the collar and the band, and a standard cotton lining 2.5 yards per pound was used in both. The control collar was made in the normal way known .to shirt makers; the top was assembled, turned and top stitched. This top was then attached to the band and the assembly sewn to a bib. A second collar was prepared in exactly the same way, except .that the comb-like element of Example 4 was temporarily sewn into every seam and then removed. The collars were made according to a size sixteen pattern and carefully measured before and after one CCC-T-19la wash cycle. They were pressed without stretching. The result was:

Sample: Shrinkage Control collar 5%; in., 2.3% Collar made with .O12 filaments IAQ in., .4%

Example 7 Soft collars were made as above, but a different comblike structure was used to reduce the shrinkage potential of the test collar. A dense row of natural bristles was laminated between two thin sheets of cellulose acetate plastic, so that about three-quarters of an inch of each bristle protruded in a parallel arrangement from one side of the laminate. The bristles, probably hog bristles, were quite round and quite uniform and averaged about .1018" in diameter. There were about 45 protruding per inch of the edge of the laminate which was about 18 inches long. This was sewn into every seam of the test collar as the collar was assembled. A control collar was prepared at the same time and under the same conditions except for the omission of the comb-like laminate.

The two collars were subjected to one CCC-T-l9la wash cycle and press dried without stretching. Results:

Sample: Shrinkage Control collar, 1/2 in 3% Collar made using bristles, ly in. gain .4% gain.

The examples serve to show that by the method of this discovery seam shrinkage is greatly reduced. They also show that the method is completely compatible with commercial conditions. If the filaments used to eliminate excess tightness in the seam are not larger than about .025" in diameter, the seams produced are not grossly nor obviously loose and are strong and serviceable. The chemical identity of the filaments is obviously not a critical feature of the process. The laments should be smooth, approximately round, and of from .004" to .025" in diameter. The comb-like structures mentioned are only means of handling and manipulating groups of the filaments which are the essential elements of the process. The structure which holds the non-functioning ends of the filaments is obviously not critical or limiting. The filaments can be embedded in a plastic mass or be part of a woven fabric or webbing. I have used the ravelled edge or a fabric or webbing most of the time,

merely because such are readily available examples of the comb-like structure necessary. A true comb with very fine teeth would also serve.

It will be understood that various changes in the details and materials, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim:

l. The method of joining several plies of fabric together under conditions of high speed sewing in a loose seam that will show reduced tendency to shrink and stitch pucker which comprises, stitching together said plies while they are superposed, and during the sewing introducing into approximately every stitch at least one of the teeth of a comb-like structure, said teeth being approximately round, smooth filaments .004 to .025 inch in diameter and one-quarter to three-quarter inches long, and then withdrawing the comb-like structure from the seam.

2. The method of producing a seam joining several plies of fabric together for reducing seam shrinkage and stitch pucker which comprises, stitching together said pies while they are superposed and during the sewing causing the sewing thread to encompass in approximately every stitch at least one free end of a monofilament of polyvinylidene chloride of from .004 to .025 inch in diameter, the several filaments bing held fast in approximately parallel arrangement to give an over-all superficial resemblance to a comb-like element, and then withdrawing the same filaments from the seam.

References Cited in the file of this patent UNITED STATES PATENTS 2,714,758 Woodson Aug. 9, 1955 2,730,060 Schoij Jan. l0, 1956 2,731,788 Donaldson Jan. 24, 1956 

